An electrode system to capture bioelectric signals, such as electroencephalograph (EEG) signals, from a subject generally should address various requirements including safety needs, cost, power consumption, performance, ease-of-use, appearance and subject comfort. In a non-clinical application the relative importance of these factors may be somewhat different to that in a clinical application. In a clinical application, for example, a relatively skilled technician applies the electrodes, whereas in non-clinical application, the electrodes are more likely to be applied by a person with no training or knowledge of correct application or placement of the electrodes. Convenience and subject comfort are also generally more important in a non-clinical application. A patient in a clinical situation is more likely to be tolerant of some level of discomfort or inconvenience when testing and calibrating electrodes than a person in a non-clinical setting that may need monitoring over long periods of time, without interfering with the patient's daily routines.
Conventional EEG systems use scalp level electrode attachment to monitor neurological activity. Conductive gels and pastes are often applied before placement of the scalp electrodes to improve sensitivity. However, application of conductive gels and pastes is often inconvenient and time consuming. Furthermore, conductive gels and pastes can often bleed between neighboring electrodes and cause signal contamination.
There are number of hats, helmets, and headgear that have been developed to collect EEG data without the use of collodion. However, these devices still require the assistance of a technician. Many devices are only good inside a clinic or a doctor's office and impractical for use during everyday living. There have been devices that measure EEG outside of a clinic or doctor's office, but those devises tend to be large and hard to disguise when wearing the devise and going about one's daily activity.
Some efforts have been made in the development of dry electrodes. However, available dry electrodes have a variety of limitations, including movement and interference, particularly from hair. Consequently, it is desirable to provide improved electrodes for EEG.